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  3. More than two centuries after Benjamin Franklin used one to study lightning, a team of atmospheric scientists has found that kit

More than two centuries after Benjamin Franklin used one to study lightning, a team of atmospheric scientists has found that kit

admin2009-04-27  69
问题     More than two centuries after Benjamin Franklin used one to study lightning, a team of atmospheric scientists has found that kites are a potent research tool for studying air conditions at high altitudes.
    Ben Balsley and John Briks at the University of Colorado have developed a kite and instrument package to sample the atmosphere up to 3.5 kilometers high, for up to two days at a time. The kite is cheaper and more flexible than balloons and aircraft, the traditional vehicles for atmospheric research. Within two years the team expects to fly kites up to 10 kilometers high, and Briks hopes to use these to measure carbon dioxide and methane emissions over the Brazilian rainforest and the transport of air pollutants over the Atlantic Ocean.
    The kite is a 15-square-meter Para foil made of Mylar, which ’is not only strong, but unlike nylon, Joes not absorb water. The kite "string" is made of Kevlar, famous for its use in bullet-proof vests, which is so strong that 6 kilometers of it weighs just 18 kilograms, yet can withstand a loading of 430 kilograms.
    The most innovative component of the system is the TRAM, or Tethered Rover for Atmospheric Measurements, which can move the sampling instruments ’up and down the tether while the kite maintains a constant altitude. "Our instruments measure such things as temperature, pressure, humidity, and concentrations of ozone and other air pollutants," Beasley explains. "We need to get continuous measurements, over the course of days, from various altitudes. Conventional free balloon methods can sample such parameters, but they cannot stay in any one position, and are limited to altitudes of two kilometers. Aircraft can sample at any altitude, but they are very expensive to operate, and cannot remain in one position for more than four hours."
    The TRAM, which is actually a kite-like aerofoil connected by small wheels to the kite’s tether, can be operated from the ground. It will move up and down the tether, or maintain a given altitude while the instruments sample the air. "An important cost of balloon sampling is the instrument package, which typically costs about $1000, and is always lost." Basely says "Now we can use the instruments on the TRAM, and not only get more data, but reuse it again and again," The TRAM with its instruments, including the radiotelemetry link to the scientists on the ground, weighs 6 kilograms, including batteries that can power it for two days.
    Basely and his colleagues are continuing to improve the kite and TRMA, and expand its capacities, but Basely notes that it does have its limitations: "The kite can only lift about 10 kilograms, and this means the equipment’s power requirements must be low, too. We need locations with steady, relatively strong winds, and must also avoid air traffic."
选项 A、Kites have been found to be a useful tool in research on air conditions
B、Balloons and aircraft are traditional tools in research on air conditions
C、The kites can now fly up to 10 kilometers high
D、The kites are expected to fly higher and do more researches in the near future
答案C
解析 细节题和辨析题。文章在第二段第三句提到"within two years...10 kilo-meters high"意为"该研究小组期望两年内能把这种风筝放飞到1万米高空"，可见这种想法还未实现。因此选C，其它A、B、D项分别在第一、二段中找出。
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